(1) Field of the Invention
The present invention relates to an engine cooling structure for agricultural tractors.
(2) Description of the Prior Art
A known example of engine cooling structure for agricultural tractors is disclosed in Japanese utility model publication Kokai No. 61-198119. This cooling structure comprises an engine, a forwardly blowing type cooling fan disposed forwardly of the engine, and a radiator disposed forwardly of the cooling fan. Cooling air having passed through the radiator is exhausted from the front of a hood enclosing the engine.
Another known example of engine cooling structure is disclosed in U.S. Pat. No. 4,081,050, in which a forwardly blowing type cooling fan is disposed rearwardly of an engine, and a radiator is disposed rearwardly of the cooling fan and adjacent a driver's seat. In this example, cooling air is drawn through an air inlet disposed adjacent the driver's seat and flows through the radiator and the cooling fan, past the engine, and out through the front of a hood as in the foregoing example.
These known structures in which the cooling air is exhausted from the front of the hood, as distinct from the case of exhausting the cooling air toward the driver's seat, have the advantage that the driver is not subjected to the air moving past and heated by the radiator. However, in the first-mentioned example the radiator is disposed downstream of the engine with respect to cooling air flows, the air heated by the engine acts on the radiator. Since the cooling air for removing heat from the radiator is warmer than cooling air as introduced from the ambient, sufficient heat exchange does not take place at the radiator which has the disadvantage that an increased amount of water must be recirculated through the radiator.
The second known example produces a high cooling effect for the radiator since the cooling air drawn from the ambient through the air inlet acts on the radiator first. However, since no blasting device is provided downstream of the cooling fan, the cooling air moving past the fan is prevented from flowing smoothly and disturbed by the engine having a complicated external configuration. This results in an insufficient amount of air flow thereby impairing the cooling effect. Furthermore, this known structure has the cooling fan located in the vicinity of the driver's seat, which poses the problem of noise to the driver. Such position of the cooling fan is restrictive to the range for providing the air inlet or inlets.